﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Demo1
{
    class Demo1
    {
        //圆面积
        public static void Test()
        {
            const double pai = 3.14;
            Console.WriteLine("请输入圆的半径:");
            double r = Convert.ToDouble(Console.ReadLine());
            Console.WriteLine("圆的面积为:"+pai*r*r);
            Console.ReadKey();
        }

    }
}
